oracle sqlÓÅ»¯Ö®¶à±íÁ¬½ÓÓÅ»¯
Use equality first.
ʹÓõÈÁ¬½Ó
Use range operators only where equality does not apply.
Ö»ÓÐÔÚµÈÁ¬½Ó²»¿ÉÓõÄÇé¿öÏÂÊÂÓÉÇø¼äÁ¬½Ó
Avoid use of negatives in the form of !=
or NOT.
±ÜÃâʹÓà £¡= »òÕß not
Avoid LIKE pattern matching.
±ÜÃâʹÓà LIKEÆ¥Åä
Try to retrieve specific rows and in small numbers.
³¢ÊÔ²éÕÒÌØÊâµÄÁкÍÔÚСµÄÊýÄ¿ÖÐ
Filter from large tables first to reduce rows joined.
Retrieve tables in order from the most highly filtered table downwards;
preferably the largest table has the most filtering applied.
¹ýÂË´ó±í¼õÉÙÁ¬½ÓµÄÐÐÊý£¬´Ó¹ýÂ˶àµÄ±íÏòϲéÕÒ£¬¾¡¿ÉÄܵĹýÂË´ó±í
Tip
The most highly filtered table is the table having the
smallest percentage of its rows retrieved, preferably the largest
table.
Use indexes wherever possible except for very small
tables.
³ý·ÇºÜСµÄ±í£¬ÎÞÂÛʲôÇé¿ö¶àÓÐË÷Òý
Let the Optimizer do its job.
ÈÃÓÅ»¯Æ÷×öÓÅ»¯
Ïà¹ØÎĵµ£º
OracleϵÁУºÍ¼Æ¬µÄ´æ´¢
Ò»£ºÊ²Ã´ÊÇ´ó¶ÔÏ󣬴ó¶ÔÏó»ù±¾²Ù×÷£¿
²Î¼ûÎÒµÄBLOG£ºOracleϵÁУºLOB´ó¶ÔÏó´¦Àí
http://blog.csdn.net/qfs_v/archive/2008/05/21/2464599.aspx
¶þ£¬Í¼Æ¬µÄ´æ´¢»ò¶þ½øÖÆÎļþµÄ´æ´¢
1£¬ÏȲåÈëÆÕͨÊý¾Ý£¬Óöµ½´ó¶ÔÏóÁÐʹÓÃempty_blob()¹¹Ôì¿ÕµÄÖ¸Õë¡£
Àý× ......
Ò»¡¢ÏµÍ³µÄĬÈÏÓû§
Java´úÂë
sys;//ϵͳ¹ÜÀíÔ±£¬ÓµÓÐ×î¸ßȨÏÞ
system;//±¾µØ¹ÜÀíÔ±£¬´Î¸ßȨÏÞ
scott;//ÆÕͨÓû§£¬ÃÜÂëĬÈÏΪtiger,ĬÈÏδ½âËø
¶þ¡¢µÇ½
Java´úÂë
sqlplus conn / as sysdba;//µÇ½sysÕÊ»§ ......
1. ²éѯÊý¾Ý¿âÏÖÔڵıí¿Õ¼ä
select tablespace_name, file_name, sum(bytes)/1024/1024 table_size from dba_data_files group by tablespace_name,file_name;
2. ½¨Á¢±í¿Õ¼ä
CREATE TABLESPACE data01 DATAFILE '/oracle/ ......
ÎÒÃǶ¼¶¼ÖªµÀÔÚcontrolfileÖмǼ×Åÿһ¸öarchivelogµÄÏà¹ØÐÅÏ¢£¬µ±È»ÃÇÔÚOSÏ°ÑÕâЩÎïÀíÎļþdeleteµôºó£¬ÔÚÎÒÃǵÄ
controlfileÖÐÈÔÈ»¼Ç¼×ÅÕâЩarchivelogµÄÐÅÏ¢£¬ÔÚoracleµÄOEM¹ÜÀíÆ÷ÖÐÓпÉÊÓ»¯µÄÈÕÖ¾Õ¹ÏÖ³ö£¬µ±ÎÒÃÇÊÖ¹¤Çå³ýarchiveĿ¼ÏµÄÎļþºó£¬ÕâЩ¼Ç¼²¢Ã»Óб»ÎÒÃÇ´ÓcontrolfileÖÐÇå³ýµô£¬Ò²¾ÍÊÇoracle²¢²» ......
Ç°¼¸ÌìÃæÊÔµÄʱºòÃæÊÔ¹Ù²ÅÎʹýÎÒORACLEµÄÌåϵ½á¹¹£¬ÈÃÎÒÔÚÒ»ÕÅ°×Ö½ÉÏ»³öÀ´¡£»ØÍ·ÏëÏ뵱ʱ´ðµÃ»¹²»´í£¬´ó²¿·ÖÄÚÈݶ¼ÃèÊö³öÀ´ÁË£¬ºÇºÇ£¬¸Õ²ÅÔÚÍøÉÏ¿´µ½Ò»Æª½²½âORACLEÌåϵ½á¹¹µÄÎÄÕ£¬¾õµÃ²»´í£¬×ª¹ýÀ´´æ×Å£¬½«À´¿ÉÄÜ»áÓõ½¡£
=================================================================================
ÔÚ±¾ÎÄÀ ......